@ CHIYODA CHEMICAL ENGINEERING & CONSTRUCTION CO., LTD.

P. 0. Box 10 Tsurumi, Yokohama, Japan

IN5 19 AS CATALYST TUBE MATERIA

TAKA0 KAWAl LElF RUMP KATSUAKI TAKEMURA BENNY DANIELSEN

TOSHIKAZU SHlBASAKl JOHANNES WRISBERG of of

Chiyoda Chemical Engineering Holdor Tops#e A/S & Construction Co., Ltd.

For The 1982 Ammonia Symposium a t 10s Angeles 14-18 November

INTRODUCTION

A t San Francisco i n 1979 and a t the Montreal meeting in 1981, we presented

metallurgical and mechanical properties of HK40 material based on long-term

creep rupture t e s t s and the resu l t s of destructive inspections on used

ca ta lys t tubes ( I ) , ( 2 ) . We also suggested selecting stronger and more

duc t i le al loys f o r the ca ta lys t tube material ra ther than the t radi t ional

HK40, i.e. a l loys developed from HK40 such as the IN519 (24Ni/24Cr Nb),

Hika and BST al loys .

Haldor Topsbe A/S and Chiyoda Chemical Engineering & Construction Co., Ltd.

have for the past e ight years specified IN519 f o r ca ta lys t tubes as being

preferable t o HK40, both f o r new ins t a l l a t i ons and f o r retubing exis t ing

reformers. Today, 3,400 s e t s of IN519 ca t a lys t tubes are in service f o r 30

HTAS reformers without any reported problems.

This paper i s concerned w i t h technical and economic improvements i n

reformers through the u t i l i za t ion of IN519 as ca ta lys t tube material. I t

also deals w i t h the proven superior charac te r i s t ics of IN519 based on

metallurgical t e s t s on aged specimens and f i v e sample ca ta lys t tubes which

had been removed from three reformers a f t e r one, three, and six years of

service.

DESIGN OF REFORMERS WITH IN519

The creep damage i n ca ta lys t tubes i s accelerated by thermal s t resses due

t o temperature gradients i n the wall , especia l ly repeated high s t r e s se s from shutdown and s tar t -up. Certain properties in materials a re desi rable

a s such properties tend t o reduce o r prevent creep damage. Increasingly,

the following desi rable properties have been recognized:

(1) High rupture strength which permits th inner walls , result ing i n a decrease in tube-metal temperature and thermal s t r e s s .

(2 ) Higher rupture d u c t i l i t y which relaxes the thermal s t resses .

Several a l loys have been developed w i t h a 20 t o 30 percent higher creep

rupture strength a s well a s higher duc t i l i t y than HK40. The chemical

compositions of these a l loys a r e compared in Table 1.

IN519 was selected from these a l loys mainly because actual plant experience

had been reported and IN519 tubes were comparable t o HK40 in price since

they contain only 24 percent nickel. IN519 was developed from HK40 by INCO

Europe Limited i n the ear ly 1960's and i n 1968 the f i r s t IN519 ca ta lys t

tubes were applied in a commercial reformer furnace.

In order t o examine performance under process conditions and t o determine

economic f e a s i b i l i t y , many reformers were designed t o compare two possible

ca ta lys t tube mater ia ls , HK40 and IN519. Table 2 shows the data of s i x

selected reformers of d i f fe ren t design.

As a basis f o r t h i s comparison, the same production r a t e corresponding t o 1,000 MTPD ammonia has been selected f o r the design of reformer furnaces

assuming the following conditions.

( 1 ) Feed Stock : Natural Gas CH4 : 96.5 vol. %

C2H6 : 3.0 vol. %

C 3 H 8 : 0.5 v o l . %

(2 ) Reformer Type : Topsde's Radiant Wall Type

Case 1 i s a base case w i t h HK40 re f lec t ing what may be considered as f a i r l y

conventional reformer operating conditions using a steam t o carbon r a t i o of 2 3.6 and an average internal heat f lux of approximately 70,000 Kcallm hr.

Cases 2,3 and 4 w i t h IN513 a l s o possess a steam t o carbon r a t i o o f 3.6 and

are designed t o main ta in some cond i t i ons f o r comparison w i t h t h e base case.

As seen i n Table 2, f o r a l l IN519 cases, the maximum tube w a l l temperatures

were lowered and t h e i n n e r tube diameters were increased.

I n Case 2 w i t h t h e same number o f c a t a l y s t tubes as i n Case 1, t h e requ i red

heated l e n g t h was shortened about 5 percent and t h e pressure drop through 2 the c a t a l y s t bed was decreased 0.5 Kg/cm . I n add i t i on , Case 2 had t h e

same peak heat f l u x as Case 1.

Case 3 was ab le t o reduce t h e c a t a l y s t tube number about 4 %, w h i l e

ma in ta in ing t h e same heated l eng th and t h e average heat f l u x .

The b igges t reduc t i on i n t h e c a t a l y s t tube number, about 9 %, was obta ined

i n Case 4, where t h e heated l eng th and t h e pressure drop were kept t h e

same as i n Case 1.

Cases 5 and 6 i n Table 2 a l so used IN519 tube ma te r ia l , these cases

demonstrate c h a r a c t e r i s t i c data f o r an ammonia p l a n t w i t h increased heat

f l u x and a steam t o carbon r a t i o o f 3.0 i ns tead o f 3.6. The decrease i n

t h e steam t o carbon r a t i o requ i res an increase i n t h e e x i t gas temperature

o f about 20°C. Both t h i s change and increase heat f l e x y i e l d h igher tube

w a l l temperature. Though t h e ou te r tube diameters had t o be decreased t o

pro long t h e tube l i f e , i t was poss ib le t o o b t a i n ex tens ive savings and keep

acceptable tube w a l l th ickness due t o t h e h igher s t reng th p rope r t i es o f

IN519.

Thus, by u t i l i z i n g IN519 c a t a l y s t tubes i ns tead o f HK40 tubes, t echn ica l

and economic improvements have been made i n t h e design o f reformer

furnaces. Through r e t u r b i n g p r o j e c t s , we have a l s o adapted e x i s t i n g

reformers t o be i n s t a l l e d w i t h IN519 c a t a l y s t tubes apply ing updated

engineer ing and design technology.

The aforementioned m o d i f i c a t i o n s have been repo r ted (3). One such

m o d i f i c a t i o n took p lace on a 1,000 MTPD ammonia p l a n t a f t e r 8 years o f

operat ion. By r e p l a c i n g HK40 ma te r ia l t o IN519 and by rearrangement o f t h e

tube layout from a staggered row to a s ingle snaked row, the number of

ca ta lys t tubes was reduced from 300 t o 204, a reduction of 96, with no

change in the reformer furnace i t s e l f nor the process conditions. Once

implemented, these modifications were proven successful during actual plant operation.

METALLURGICAL EXAMINATION O F IN519 CATALYST TUBES

I t i s necessary t o examine the cha rac t e r i s t i c s of materials which have been

used f o r a long time o r have been aged f o r a long time. Such data are compiled in order t o predict the degradation of ca ta lys t tubes and to

estimate the tube \ l ives in the actual plants. Although data on aged

materials are avai lable through laboratory t e s t s , these data a re not

necessarily very accurate nor r e l i ab l e in estimating the degradation of

ca ta lys t tubes in actual plants because the time fo r aging i s simply not

long enough. As a r e s u l t , examinations were conducted t o confirm the

properties of the IN519 material a f t e r long term use.

(1) Aging Tests:

Specimens were exposed t o f i v e d i f fe ren t environments in the steam

reformer furnaces f o r as long a s three years and the specimens

were subjected t o metallurgical t e s t s .

( 2 ) Examination of Used Catalyst Tubes:

Metallurgical examinations were conducted on f i v e used ca ta lys t

tubes which were taken as sample tubes from two hydrogen plants and an ammonia plant.

RESULTS OF AGING TESTS

The chemical composition of the spun c a s t tubes used f o r the aging t e s t i s

shown in Table 3 . The IN519 and HK40 t e s t coupons and t h e i r weld jo in t s

were exposed t o f i v e d i f fe ren t environments including two t ransfe r l ines

f o r the reformed gas, the e x i t of a secondary reformer and two i n l e t s of convection zones of reformer furnaces, a s shown i n Table 4.

Metallurgical and mechanical examinations were conducted a f t e r aging of

one, two and three years. To compare the aging conditions, the

Larson-Miller Parameter, L.M.P.=T(log t +16)x10-~, was used as the aging

parameter. These aging parameters for each t e s t coupon a re a lso l i s t e d i n

Table 4.

Microscopic Examinations

Photograph 1 shows the microstructures of IN519 and HK40 i n as-cast

condition. Photographs 2, 3 and 4 show the microstructures of aged

materials. When the aging parameter was low such as 20.3 and 21.0 and

the tubes were aged a t around 750°C, many f ine secondary carbides

precipitated a t the interdendri t ic region. Small amounts of sigma

phases were found i n specimens w i t h an aging parameter of 20.3.

As the aging parameter increased, the primary and secondary carbides

coarsened. The amount of secondary carbides and sigma phases was l e s s

than those i n HK40. The coarsening of carbides i n IN519 seemed t o

occur more quickly than in HK40 as seen i n Photographs 3 and 4.

Tension Tests a t Room Temperature

Figures 1 , 2 and 3 show the resu l t s of the tension t e s t s a t room

temperature a f t e r aging. The changes i n the t ens i l e strengths of the IN519 tubes and weld jo in t s a f t e r aging were less than those of HK40.

The behavior of the 0.2 % proof s t resses were ra ther s imilar t o those

of HK40. Although the data on elongation and reduction of area of IN519 were widely spread when plotted , t h e i r values were higher than

those f o r HK40 a t higher aging parameters.

Impact Tests

Figure 4 shows the comparison of Charpy impact values a t room

temperature on aged IN519 and HK40. The change of the impact values

of the IN519 and HK40 by aging corresponded t o the change i n

elongations a t room temperature tension t e s t s .

(4 ) Hardness Tests

F igure 5 shows t h e change i n hardness a f t e r aging. The hardness

showed t h e maximum value a t the aging parameter around 20.5 t o 21.5

and decreased as t h e parameter increased. This behavior was s i m i l a r

t o t h a t o f HK40.

1 (5) Creep Rupture Tests

To con f i rm the pub l isned rup tu re data, creep rup tu re t e s t s were

conducted on t h e IN519 spun cas t tubes and t h e weld j o i n t s as shown i n

F igure 6. The data taken on the new IN519 spun cas t tubes reasonably

fo l lowed t h e mean values o f t h e master curve presented by INCO (4) .

Although almost a l l data f e l l w i t h i n t h e s c a t t e r range, t h e r u p t u r e

st rengths o f weld j o i n t s were somewhat lower than those o f t h e base

metals.

Creep rup tu re t e s t s were a l so done on t h e aged specimens.

F igure 7 shows the r e s u l t s of t h e creep rup tu re t e s t s on t h e base

metals and weld j o i n t s which were aged a t approximately 920°C f o r two

years (aging parameter : 24.1). The rup tu re st rengths decreased

somewhat due t o t h e change o f mic ros t ruc tures by aging. However, as

shown i n F igu re 8, t h e rup tu re s t rengths o f 1,000 hours o f IN519 base

ma te r ia l as w e l l as weld j o i n t s , were s t i l l h i ghe r than those of HK40

f o r each aging cond i t i on .

F igure 9 shows the comparision o f t h e rup tu re d u c t i l i t i e s o f aged

IN519 and HK40. The rup tu re d u c t i l i t i e s decreased as the r u p t u r e t ime

increased f o r bo th ma te r ia l s . The minimum value o f IN519 was h ighe r

than t h a t o f HK40 and was almost the same as the maximum value o f

HK4O.

EXAMINATION ON USED CATALYST TUBES

F i v e IN519 c a t a l y s t tubes have been i nves t i ga ted des t ruc t i ve l y . The

ope ra t i ng cond i t ions o f these c a t a l y s t tubes are shown i n Table 5. Test

i tems f o r examination o f each c a t a l y s t tube are l i s t e d i n Table 6. The

original location of t e s t pieces used i n examinations are a lso shown i n

Table 6 f o r the case of the S4 ca ta lys t tube. The t e s t resu l t s a r e a s

follows.

(1) Nondestructive Tests

To inspect deformation due to creep, dimensional checks were done. No

meaningful deformation was observed f o r a l l tubes. Radiographic Tests

(RT) and Dye-Penetrant Tests (PT) conducted on both the outer and

inner surfaces f o r every weld zone, indicated no f au l t s due t o creep

damage on a l l of the ca ta lys t tubes.

( 2 ) Tension Tests

Figures 10 and 11 show the summary of tension t e s t s a t room

temperature f o r a l l ca ta lys t tubes. The data a r e plotted along the

length coordination where "Location 0" means the i n l e t and "Location

100" re fe rs t o the ou t l e t of a ca ta lys t tube. The i n l e t of t he ca ta lys t tube o r so called "cold end" i s out of the furnace, and the

service temperature i s about 400-450°C. Since t h i s temperature is not

so high as t o age the heat res i s t ing al loy, the mechanical properties

of t h i s par t re ta in the as-cast condition.

Although change i n the t ens i l e strength along the length coordination

was d i f fe ren t from tube t o tube, the t ens i l e strengths tended t o

decrease a s the used period became longer as shown i n Figure 10.

Changes i n the 0.2 % proof s t resses a t room temperature were

re la t ive ly small f o r a l l sample tubes, as expected from the aging

t e s t .

Figure 11 shows the elongation a t room temperature. Generally, the

d u c t i l i t y was reduced greatly a t "Location 10" close t o the top of t h e

tubes, though changes i n the elongation along the tube length were

d i f fe ren t f o r each tube.

Tension t e s t s were a l so conducted a t 87loC and the r e su l t s a re shown

in Figures 12 and 13. The data on t ens i l e properties a t 871°C

indicated t h a t the range of these properties was not as g rea t as t h a t

shown by t e s t s conducted a t room temperature.

(3 ) Microscopic Examinations

To inspect the creep damage i n d e t a i l , microscopic examinations were

conducted on four longitudinal sections of every weld zone. No

f i s sures o r no aligned voids due t o creep were detected on a l l of the

specimens taken from every ca ta lys t tube.

Photograph 5 shows the microstructures of "Location 10" and "Location

70" of the S5 Tube which was used f o r s i x years. The service

temperature a t "Location 10" was lower than tha t of "Location 70".

The microstructure of "Location 10" showed many f i ne secondary

carbides and needlelike sigma phases. In "Location 70" the primary

carbides and the secondary carbides were coalesced and coarsened, and

the number of the secondary carbides was few.

Compared t o the microstructures of HK40 tubes shown in Photograph 6

which were exposed t o s imilar service conditions, the amount of

secondary carbides i n the microstructures of IN519 was l e s s and the

r a t e of coalescence seemed t o be f a s t e r i n IN519. A small amount of

blocky sigma phase was observed.

(4 ) Creep Rupture Tests

Creep rupture t e s t s were conducted on the specimens taken from the 53

tube which was used f o r three years. Test specimens were taken from

three par t s of the tube: one was from the cold end and the others were

one quar ter and two-thirds from the top of the tube, areas qf high

service temperature. Figure 14 shows the resu l t s . The specimens from

high temperature par t s showed somewhat lower rupture strengths than

those from the cold end.

DISCUSSION

(1) Mechanical Properties of Aged IN519 Material

1 ) Creep Rupture Properties

I t i s generally recognized t h a t creep rupture elongation as well

as creep rupture strength of the IN519 material i s higher than tha t of the HK40 material i n the as-cast condition. The same

relation was found t o be t rue of specimens which were aged for as

long a s three years , proving the superiori ty of IN519 over HK40 i n

the creep rupture strength and duc t i l i t y f o r long term use.

2 ) Ducti l i ty i n Tension Tests a t Room Temperature

The elongation and t h e reduction of area in tension t e s t s a t room

temperature of aged material are not the major parameters which

a f f ec t ca ta lys t tube l i f e . Materials having higher duc t i l i t y a t

room temperature a r e preferable f o r ca ta lys t tube use, because

duc t i le material i s more res i s tan t t o f a i l u r e caused by thermal

shock or sudden change of service temperature which might occur

during an emergency shut down.

The resu l t s of the tension t e s t s on the used IN519 ca ta lys t tubes

revealed t h a t the t ens i l e properties of each ca ta lys t tube was d i f fe ren t , especially the elongation values a t room temperature.

This variation i s assumed t o come from chemical composition and

production procedures. The e f fec t of chemical compositions on the

elongation i n the t e n s i l e t e s t s a t room temperature of the aged

IN519 material was analyzed.

Figures 15, 16 and 17 show the e f f ec t of carbon, s i l icon and

manganese, respectively, on the elongation a t room temperature.

In t h i s analysis, the data was divided in to three groups using the

service temperatures of the catalyst tube regardless of the used

periods. The f i r s t group contained data from the cold end, which nearly represented the properties of unused materials. The second

group consisted of data from "Location 5" t o "Location 30" whrrc

the service temperature was not as high as t h a t i n the thi rd

group. The t h i r d group inc luded data f rom "Locat ion 30" t o t h e < o u t l e t , where t h e se rv i ce temperature was highest. The e f f e c t o f

chemical composit ion on the e longat ion values o f unused mater ia l

was i n s i g n i f i c a n t as was revealed upon ana lys is . S i m i l a r

r e l a t i o n s h i p s demonstrat ing the e f f e c t s o f c e r t a i n elements on the

e longat ion were obta ined f o r the second and t h i r d groups and are

summarized as f o l l o w s :

O Carbon(Fig.15) and Niobium have no s i g n i f i c a n t e f f e c t .

O S i l i c o n ( F i g . l 6 ) , Phosphor, and S u l f u r have negat ive e f fec ts .

" Manganese(Fig. l 7 ) , N icke l and Chromium have p o s i t i v e e f f e c t s .

(2) Comparison o f IN519 and HK40 Cata l ys t Tubes on Creep Damage

Long i tud ina l creep damage i n t h e base metal o f HK40 c a t a l y s t tubes

which had been used as l o n g as several years was o f t e n reported. And

c i r cumfe ren t i a l creep damage a t t h e weld metals was a l s o observed on

the HK40 c a t a l y s t tubes which had been used beyond th ree years. These

cracks were caused by thermal s t ress due t o t h e temperature grad ien t

i n t h e wa l l .

However no such creep damage was observed i n the IN519 c a t a l y s t tubes

which had been used up t o s i x years. Th is was main ly a t t r i b u t e d t o

the h igher rup tu re s t r e n g t h and rup tu re d u c t i l i t y o f IN519.

CONCLUSION

Creep rupture strength and creep rupture duc t i l i t y of IN519 spun c a s t

material a r e confirmed t o be higher than those of HK40 material even a f t e r long time use.

Use of IN519 due t o increased rupture strength yields thinner wall

design and reduces thermal s t ress .

Suscept ibi l i ty t o creep damage of IN519 ca ta lys t tubes i s lower than

tha t of HK40 ca ta lys t tubes based on destructive examinations of IN519

ca ta lys t tubes indicating no tube damage a f t e r as much as s ix years

use.

The d u c t i l i t y of IN519 a f t e r aging i s affected different ly by chemical

compositions such as Si and Mn. Carbon have no s ign i f f ican t e f f e c t on

the duc t i l i t y .

By u t i l i z i n g IN519 as ca ta lys t tube material , the following technical

and economic advantages can be obtained:

" Decreased costs resultant of improved, compact reformer design

O Extended operating range

" Increased operating re1 iab i l i t y

O Lower fuel consumption

All these improvements were ver i f ied during actual commercial plant operations.

REFERENCE

T. Kawai, K. Takemura et al, "Effect of Macrostructure on Catalyst Tube Damage and Creep Rupture Properties of HK40t1, AIChE Ammonia Plant Safety, Vol. 22, pp. 119-30, 1980.

T. Kawai, T. Takemura et al, "Creep-Rupture Properties of HK40 Spun Cast Tubes", AIChE Plant/Operation Progress, Vol. 1 No.3, pp. 181-6, July 1982.

N. Moriya, T. Kawai & H. Uchida, "Technical and Economic Improvements from Catalyst Tube Modifications in Steam Reforming Plant", Bulletin of Arab Federation of Chemical Fertilizer Products, No. 67, pp. 15-24, May 1981.

INCO Europe Limited, INCO Data Books "IN519 Cast Chromium-Nickel-Niobium Heat Resisting Steel1', 1976.

i

c Table 1 Chemical Compositions of Catalyst Tube Alloys

Alloy Other

1 BST 25 20 0.45 0.6 Ti

Table 2 Comparison of Reformer Designs*

Case 1 2 3 4 5 6

Tube Material HK 40 IN 519 IN 519 IN 519 IN 519 IN 519

Number of Tubes 186 186 178 170 166 188

Max. Tube Wall Temp. 891 886 883 886 900 891 ("C)

Ave. Heat Flux 69,800 69,300 69,800 72,500 75,300 82,000 (Kcal/SMh)

Heated Length 11.5 - 11.0 11.5 11.5 12.2 12.1 (4

Pressure Drop.. .old 2.3 1.9 2.1 2.3 2.8 4.4 (Kg/SCM)

Outer Tube Diameter 152 152 152 152 142 115 (m)

Inner Tube Diameter 115 121 121 121 110 90 (mm)

* Boldface type indicates conditions matching Case 1

Table 3 Chemical Compositions o f Spun Cast Tubes Used f o r Aging Tests

T.C: Test Coupon

Table 4 Sumnary o f Aging Test Condit ions

T.L. : Transfer L i n e C.Z. : Convection Zone Bottom S.R. : O u t l e t o f Secondary Reformer A.P. : Aging Parameter, T(1og t + l 6 ) x l 0 - ~ , T(OK), t (hou r ) Temp.: (OC)

Photograph 1 Microstructures of IN519 and HK40 As-Cast Condition

(2) HK40

Photograph 2 Microstructures of IN519 and HK40 After Aging (A.P.=20.3)

Pho tog raph 3 M i c r o s t r u c t u r e s o f IN519 a n d HK40 After Aging (A.P.=22.7)

- 17 -

Photograph 4 M i c r o s t r u c t u r e s o f IN519 and HK40 A f t e r Aging (A.P.=24.1)

20 0 20 21 22 23 24

hging Parameter = T(log t +16)/1m

Fig. 2 comparison of Tensile Strengths at Room Temperature of

IN519 and HK40 Weld Joints After Aging

b Teat Coupon IN519 Oh B < 0 HK40 AD 7

Y 1 I 1

0 -

20 21 22 23 24

Aging Parameter = TUog t +16)/1000 Fig. 3 Comparison of Ductilities of Tension Test at Room Temperature

of IN519 and HK40 After Aging

I 1 I I

0 20 21 22 23 24

Aging Parameter = T(lag t +16)/1888

Fig. 4 Comparison of Charpy Impact Values at Room Temperature of

of IN519 and HK40 After Aging

Teet C o u p IN519 OA OC HKM VE

Aging Parameter = T (log t +I61 /I000

Fig. 5 Change in Vickers Hardness of IN519 and HK40 After Aging

Fig. 6 Results of Creep Rupture Tests on IN519 Spun Cast Tubes

17 18 19 20 21 22 23 24 25 26

L. M. P. = T (log t +16) /I000

Fig. 7 Results of Creep Rupture Tests on Base Metals and Weld Joints

of IN519 After Aging 2 years at 920°C

Aging Parameter = TClog t +16)/1000

7.0

G 6.0

E < 5 .0 -

6 m m " 4.0- PI L

-9 cn

Fig. 8 Comparison of 1,000 hour Rupture-Strengths of Aged IN519 and HK40

IN519 09- Metal OVdd Metal M40 @bee Metal .Veld Metal

- --4.-

/--

K.-' . . . . . \ ---a x

--. . __--- - . . .,----- - - \-* Y

Fig. 9 comparison of Rupture-Ductilities of Aged IN519 and HK40

50

3 4 0 - . c 0 ." 4

& 30 I: 0

A

W

20 3 4 P 3 II:

l0

0 10

- - 50 100 500 1000

Rupture Time (houre)

. -. . D IN519 0A.P. <21 D A . P . ~ OAe h e HK40 @A. P. <21 DA. P.Q1 +Am Coe 0 . 0 . + 0 0 .

0 a n 0. 0" "@0 =y. 0 . 0 - 0 0

@ 0.

- 8 .. IN519 Minimum

- * 8 * \-.zT W e + 1 8 . t * o u * -

I * 1 1 -+ + I I

Table 5. Service Conditions of IN519 Catalyst Tubes

Catalyst Tube No.

Plant 17: Tube Maker

Table 6. S4 Tube Test Items and Locations

Dimension Check

Chem. Analysis

Macrostructure --w 0 0 0

Microstructure 10 1 0 1 0

Tension Test

Creep- Rupture 1 0 1

Bottom

Location Fig. 10 Results of Tension Tests at Room Temperature on Used Catalyst Tubes

0 20 40 60 80 10E

Location

Fig. 11 Results of Tension Tests at Room Temperature on Used Catalyst Tubes

- 25 -

Location

Fig. 12 Results of Tension Tests at 871 "C on Used Catalyst Tubes

Location

Fig. 13 Results of Tension Tests at 871 "C on Used Catalyst Tubes

(1 ) Upper P o r t i o n (Loca t ion 10)

( 2 ) Lower P o r t i o n (Loca t ion 70)

Photograph 5 M ic ros t ruc tu res o f IN519 Ca ta l ys t Tube Used f o r 6 Years

x 100 x 400

( 1 ) Upper P o r t i o n (Locat ion 10)

( 2 ) Lower P o r t i o n (Locat ion 70)

Photograph 6 M ic ros t ruc tb res o f HK40 C a t a l y s t Tube Used f o r 6 Years

20.0. I 0 Cold End 1/4 from TOP O2/3 from TO

2.01 I I I I , I

10 50 100 500 1000 5000 10000

Rupture Time (hours)

Fig. 14 Results of Creep Rupture Tests on Used Catalyst Tubes

- C o l d End Looation 5 t o 30 A Loootion 30 t o 101

.27 .28 .29 .30 .31 .32 .33 .34 . 3 5

Corbon Content (2)

Fig. 15 Effect of Carbon Content on Elongation at Room Temperature of IN519

Silicon Content ( X )

Fig. 16 Effect o f Silicon Content on Elongation at Room Temperature o f IN519

30 C o l d End CI Loomtion 5 to 30 A Loootion 30 to 101

.50 .60 .70 .80 .OO 1.00

Manganeee Content (27

Fig. 17 Effect o f Manganese Content on Elongation at Room Temperature o f IN519